Related Art
The invention is based on a circuit for operating an electric motor, of the type having an arrangement that produces a signal serving as a measure for the rpm of electric motor and having a monitoring arrangement for detecting an increased load state of the electric motor. DE-PS 30 34 118 discloses a generic circuit that has a sensor which produces a signal serving as a measure for the rpm of the electric motor. The known circuit includes a monitoring arrangement for ascertaining an increased load state of the electric motor; the arrangement monitors rpm, comparing the actual rpm determined from the sensor signal to a predetermined limit value. The limit value is derived from an initial actual rpm value established after a predetermined time following startup of the known circuit. The known circuit for operating an electric motor is used in electronic monitoring of an opening and closing process of electrically-operated motor vehicle parts. The limit value is tailored to the task of detecting jammed objects or body parts. The known circuit is not provided with an increased load state of the electric motor, or of a provided end stage, that can lead to a thermal overload of these parts.